Hydrogen ion exchange apparatus



June 20, 1944. F. w. WHITLOCK 2,351,643 I HYDROGEN ION EXCHANGE APPARATUS zin June 20, 1944.

F. W. WHITLOCK HYDROGEN ION EXCHANGE APPARATUS Filed Aug. 1, 1940 2 Sheets-Sheet 2 Patented June 20, 1944 2,351,648 HYDROGEN ION EXCHANGE APPARATUS Fred W. Whitlock, Rockford, Ill., assignor to Antomatic Pump & Softener Corporation, Rockford, 111., a corporation of Illinois Application August 1, 1940, Serial No. 349,351

'15 Claims.

My invention relates to improvements in water treatment devices wherein means are provided for preventing the device from being prematurely returned to service. Means are also provided for indicating the condition of the effluent of the device.

A serious problem is encountered in the-treatment of water through a device employing a tankand a bed of so-called carbonaceous zeolite," such as the hydrogen exchange type. Devices of this type are frequently used as .a source of treated water for use in bottling soft drinks. if the regenerating steps of such a device are not carefully watched and checked, there is great likelihood of prematurely returning the device to service. The common. practice in such softeners is to introduce an acid solution through the bed of zeolite to regenerate it by an exchange of hydrogen for the metals retained by the zeolite during the treating process, the spent acid being conducted to a drain. The next phase of regeneration is a rinse step in which water is introduced to rid the softener of the salts of the metals given up by the zeolite and any excess acid. It is apparent that if the softener is returned to service prior to a complete rinsing, acid may be carried into the service line where it may do irreparable personal damage if the treated water is used for the bottling of soft drinks intended for human consumption, as well as damage to physical equipment such as a boiler through its corrosive action. It is therefore the principal object of my invention to provide a device for detecting the presence of a predetermined amount of acid or other electrolyte in theefliuent and automatically open or close a valve on the service line in accordance with the type of solution present, so that regardless of the operators errors, no undesired electrolytic solution will pass through the service line.

Another object of my invention is to provide a device of relatively great sensitivity for detecting a predetermined electrolytic solution and for passes downward through a. zeolite bed I to en-' operating valves and signals in response to the presence or absence of such a solution. Toobtain the sensitivity required for detecting undesired acid solutions, for example, it is necessary that such a device tolerate weaker acid or other electrolytic solutions without a positive response thereto. This object is accomplished in my invention by providing a cell through electrodes immersed in theiiquid to be tested, together with a circuit balanced so that no current will flow through the circuit when an electrolytic solution less than the predetermined one is present in the cell and a galvanometer responsive to unbalancing of the bridge in one direction to actuate a valve for controlling the flow through the service line.

Other objects and advantages will appear from the following description and the accompanying drawings, in which- Fig. 1 is a side elevation of a zeolite water softener showing the magnetic valve, cell, control box, signal. lights, and conduits of my invention connected therewith;

Fig. 2 is a cross-section of a cell used in my invention showing the electrodes and electrolytic compartment;

Fig. 3 is a section on the line 33 of Fig. 2;

Fig. 4 is a wiring diagram showing the parts performing the electrical phases of my invention, and

Fig. 5 is a face view of the galvanometer dial.

Referring to the drawings, 8 represents a treatment tank containing a bed of hydrogen exchange zeolite i at the level indicated. Raw water is passed into a multi-port rotary valve 8 of a conventional design, such as that shown in Daniels Patent 2,093,692, through an inlet pipe 9. When the valve is in the service position III, as indicated in Fig. l, raw water enters the tank 6 through a vertical pipe H. The water then ter the lower end of a vertical pipe 14 from which it is returned to-the rotary valve 8 and directed into a service line 15.

Where it is desired to proportion the amount of treated water to raw water, a by-pass arrangementis employed, consisting of a pipe l6 which connects into the raw water inlet pipe 9 at one end circumventing the treatment tank to connect with the service line l5 through which the'treated water passes, a valve 11 being provided to regulate the proportion of raw water to treated water.

During the backwash phase commonly provided in such devices, the valve handle I8 is moved from the service position III to the opposite position I. This causes water from the inlet pipe 9 to enter vertical pipe I and pass out through its lower end located in the bottom of the tank 6. The introduction of this water acts to displace the water thereabove in the tank 6, causing it to flow out through a drain pipe I9 whose upper end also terminates in the valve 8 and provides an open passage for the direction of the water through the drain l9 when the valve lever I 8 is at the raw water by the zeolite.

haustion, acid, most commonly sulphuric acid, is introduced into the treatment tank 8 through a pipe 2| having one end located in the bottom end of a hermetically sealed measuring bottle 22, the other end terminating in a valve port with which an injector is brought into registration when the valve 8 is brought into position II.

A pipe 23 also enters the top of measuring bottle 22, its other end terminating in a T on pipe 24 which connects with the pipe 2|, control valves 25, 28, and 21 being provided on this system. Thus, when the valve lever i8 is placed in. the regenerating position II, raw water from the inlet pipe 9 will be caused to now through the injector past the valve end of the pipe 2| reducing the pressure in pipe 2! through which acid in the measuring bottle 22 will be caused to enter the raw water stream and mix therewith. This acid mixture then flows upwardly through the vertical pipe' I l and downwardly through the zeolite bed I where the hydrogen of the acid is exchanged for the metallic ions absonbed from This spent acid solution which includes the sulphates such as calcium. magnesium and sodium and excess acid enters the lower opening 01' pipe It in the bottom of the zeolite bed 1 passing upwardly therein to the valve 8 and thence out the drain pipe it.

After the required amount oi acid is intro duced into the tank 6. the device goes into the rinse step. This is accomplished by closing valves 28 and 21. therebv shuttine oi? the source of acid from the measuring bottle 22. but permittin water to continue to pass through the zeolite l and out the drain I 9. While in the rinse step, the injector permits the refilling of the measuring bottle 22 from a carbov 28. since by o enin valve 28. a reduced pressure is formed in bottle 22 causing acid to flow from the canboy 23 through a pipe 28. to the bottle 22.

From the above description it will be seen that the valve 8 is so constructed that when it is in the service position III the eltluent will leave the tank 6 through the pipe H to enter the valve 8 where it is directed into the service line I8.

Electrodes 82 and 88 oi two dissimilar metals such as Everdur (an alloy which consists of about 95% or more copper and in the region of l to 3% 01 silicon together with small amounts of other alloying agents) and stainless steel are positioned in a parallel spaced relationship within opposed couplings 84 and secured to the pipe ll of the softening tank 6 to form the electrodes of a voltaiccell. The electrodes 32 and 83 are spaced and positioned one from the other by means of three insulating disks 3B which are interposed between the inner'i'aces 31 and 38 of the couplings II and 85 and between the electrodes l2 and I3, bolts 89 being entered through the flange. portions II and 42 of the couplings to secure them together and seal an electrolyte compartment ll at the center of the insulating disk Cl. Integral arms II and 45 of the electrodes" and I! extend outwardly beyond the radius of the coupling flanges 4| and 42 to provide terminal means for the said electrodes.-

The two leads from respective terminals of the electrodes 82 and 83 are contained within a conduit. which enters a control box 81. A conduit 0 containing electrical leads for a mo.- torlzed valve 48 which is mounted on the service line II also enters the control box 81, as is illustrated in Fig. 1. Fig. 1 likewise shows the all conduit 5| containing leads for red and green signal bulbs 52 and 53.

The diagram of the circuits and other means controlling the operation of the motorized valve 49 is contained in Fig. 4. One lead 54 from the electrode 32 goes to one terminal 5B of an adjustable resistance 56 while the lead 51 from the electrode 33 goes to a moving coil galvanometer 58, the cell circuit being completed by a lead 59 which goes to the slider Bi 0! the resistance 55. Direct current is supplied to the adjustable resistance 56 and a fixed resistance We connected therewith through a rectifier 62 having leads 53 and 54 going to the ends of the resistances 55 and 56a. Alternating current from power lines 65 and 65 is directed, as reduced to approximately two volts by the tapping of a transformer 81', to the rectifier 82 through leads 88 and 89, supplying in this manner the direct current required for the resistances 56 and 58a.

The balancing of this cell circuit is accom-- plished by placing the .two sources of potential in opposition to one another so that no current will flow in the cell circuit unless the electrolytic solution in the cell compartment 43 reaches a predetermined strength. Upon reaching this strength, the potential oi the cell will increase and unbalance the circuit, causing sufliclent {3UP rent to flow through the cell circuit to actuate the galvanometer 58 notwithstanding the opposed source of potential. When resistance 55 is adjusted to balance the potential output of the cell having an electrolytic solution, such as the small acid concentration contained in treated water, no current will flow in the cell circuit. 0n the other hand, when the electrolytic solution reaches the predetermined threshold, such as an undesired acid concentration, a current will flow in the circuit of the galvanometer 5B and cause it to shift.

The valve 49 and the signal lights 52 and 53 are immediately controlled by circuits completed or broken through rocker switches M and 12 whicl'i are actuated by electromagnetic energy supplied by corresponding electromagnets l3 and W, this relay device being controlled by the movement of galvanometer 58, as will be later described. Power of approximately twenty four volts is supplied to the circuits of the electromagnets 13 and H by the transformer 51 from which leads 15 and it extend.

The circuit to each of the electromagnets i3 and 14 is designed to be completed and broken at different places, one through the switch provided by a chopper bar 11 of a conventional type chopper bar galvanometer such as that shown in McMaster and Van Guilder Patent No. 2,144,105 and the other through arms 18 and 18 of the rockers H and 12, respectively. Opposed terminals 8| and 82 of the rocker switch are in a spaced relation so that the arm 18 of rocker I I which is pivotally mounted on pin 83 will reciprocate therebetween. Likewise, terminals and 85 are positioned with respect to the arm II oi rocker '12 which is pivotally mounted on pin 88. Tension springs 81 and 88 are fastened to the rockare H and 12 to constantly urge them in an upward direction, respective inwardly located terminals 82 and 84 acting as stops against unrestricted upward urging of the springs 81 and 88. Through the provision of downwardly inclined integral end portions 8! and II on rockers II and 12, a coacting relationship is eflected in which one rocker always assumes an upward position with respect to the other, the one in the lower position being attracted thereto by the force exerted by its electromagnet While the one in the upper position is simultaneously released. Because of the reciprocable hold-down action of end portions 89and 9|, the rockers II and I2 will maintain their respective lower and upper positions notwithstanding the release of the magnetic attraction exerted by the electromagnet beneath the rocker in the lower position, the energization of the opposite electromagnet being required to reverse the positions of the rockers.

It is clear that the breaking means provided by rockers ii and E2 in the circuits of electromagnets l9 and it is in an unbroken position when a rocker is in its upward or released position. Thus, referring to Fig. 4, the circuit breaking means consisting of rocker i2 is unbroken, this portion of the circuit of electromagnet I4 consisting of lead l9, a lead 92, rocker arm I9, terminal 89 and lead 99. Correspondingly, the unbroken portion of rocker circuit of electromagnet it would consist of lead I5, a lead 99, rocker arm I9, terminal 92 and a lead 95.

Aside from the circuit breaking means consisting of the rockers ii and I2, the circuit to the electromagnets I3 and M is controlled by the lateral position of a needle 96 that is secured at one end to the galvanometer 58. As the alvanometer 58 pivots on its bearing pins 9'! and 99, it causes the needle 96 to move in a radial arc in a horizontal plane between the b-sttom edge of a cross-piece 99 of the chopper bar ll and the top edge of horizontal contact bars MI and I02. The chopper bar i1 is hinged at 603 and I04 and contains a drive arm I05 adapted to engage with a motor-driven cam I06. A continuously running electric motor I! having a rotary driving shaft I08 rotates the cam i06 causing the chopper bar TI to reciprocate in a limited are on its pivots H13 and I94. The motor I0l is supplied with power through the leads I09 and Hi which tapinto leads l6 and I from the transformer 61. As the chopper bar Ii moves in response to the turning of the cam I09, it will periodically clamp down upon needle 96 which in turn will abut the top edge of one or the other of bars IM and I02 making an electrical contact between chopper bar I1.

The valve 49 may be one of a well known type containing a solenoid which when energized opens the valve ports. When the circuit to the sole hold is broken, the valve automatically closes. In Fig. 4, the rockers II and I2 which immediately control the opening and closing of the valve 99 are shown in the open-valve position, that is, one in which the solenoid within the valve is energized. This closed circuit consists of the lead I6, a lead ill, a lead H8, 9. lead H9, lead I2i, terminal 9i, rocker arm l9, lead 94 and the lead 55. When the rockers H and I2 are moved to reversed positions through the lateral shifting of .bar 99 in response to the unbalancing of the cell circuit. the circuit to the valvellfi is broken at the terminal 9i, thereby causing the valve to close.

The green signal light 59' is tapped'by leads l2? and 829 in parallel into the valve circuit, so that when this circuit is closed the bulb will light and indicate to the operator that the service line i5 is open and that no undesired electrolytic solution is in. the cell compartment 43. Though the valve 09 is closed by the breaking of the valve solenoid circuit, a circuit to the red signal bulb 52 is completed and remains so until the solenoid valve circuit is reclosed. The cirneedle 96, and end bar IM or I02. A lead M2 from transformer lead I6 terminates at the chop per bar 11. Thus, when the needle 96 is in the position illustrated in Fig. 4, and when crosspiece 99 is in its downward clamping position, one portion of the circuit to electromagnet I3 will be completed through the leadI6, M2, the chopper bar 11, rod 96, bar I0! and a lead H3, this circuit portionbeing broken upon the return of. the cross-piece 99 to its upward position. Correspondingly, oneportion of the circuit to electromagnet 14 is completed when rod 96 is in its opposite position above the top edge-of bar I02 and when the chopper bar is in its downward clampingposition. This circuit will consist of transformer lead I6,'the lead H2, chopper bar 11, needle 96, the bar I02 and a lead I".

The galvanometer 58 is so tensioned that when no current is flowing, the needle 96 is at one side of center. The position of the galvanometer 58 is indicated on a calibrated dial II5 having an offset zero marking conforming to the zero position of the galvanometer. A right-angled end III of needle 95 moves in registration wit-h these dial calibrations to indicate the strength of the cuit of red bulb 59 consists of the leads 16, ill, I24, I25, terminal 85, rocker arm I9, leads 92 and I5. Thus, when this red bulb 52 is lighted,

the operator is informed that the valve 49 on service line I5 is closed and that there is an undesired solution of electrolyte emerging from the tank 6.

Operation When the softener is in the service position, raw water from the inlet pipe 9. enters the top of the softener to pipe II, passes downwardly through the zeolite bed I, upwardly through the pipe I6 and out the service line I5. During this stage, the treated water will contain a slight amount of acid obtained in its passage through the zeolite bed I and it may also contain some dissolved salts. These will form an electrolyte which will react with the electrodes 32 and 33. No current, however, will flow in the external circuit of this cell because of the second source of potential from resistance 56 which is opposed to the cell output in this circuit. Since the resulting balanced circuit has no current, the galvanometer 58 will seek its zero position which is indicated by the offset zero on the dial H5.

The continuously operating motor I01 rotates the cam I06 to move the chopper bar I1 in regular upward and downward movements. This periodically completes a portion of the circuit going to the electromagnet I3. The rocker 1|, however, which responds to this magnet I9 maintains its lower position as long as the needle 96 remains at the zero position or left of zero and possibly at a tolerated position one or two points at the right of zero. This setting of the rockers II and I2 completes. the circuit to the solenoid electrolytic solution within the cell compartment in the valve 49 maintaining it in open position and lighting the green signal bulb 53.

When the operator chooses to regenerate the softener, he moves the lever- I8 of the rotary valve 8, 180 to position I. This is the backwash step in which the accumulated dirt within the softening tank 6 is removed by' running raw water down through the pipe I4, up through the zeolite bed .I, and out through the drain I9.

To regenerate the zeolite, the operator now turns the valve lever I8, to valve position II,

and also opens valve 25 on the line 2| running from the measuring bottle 22 to the valve 8. Through the injector provided, a solution of water and acid is passed up through the pipe H, down through the zeolite bed 1 to regenerate the same, and up through the pipe l4 and out the drain is. when the calculated amount of acid has been introduced, the valve 25 is closed and the regeneration enters the rinsing stage through which the sulphates and excess acid are rinsed from the tank 8 by displacing the regenerating solution of acid and water with water. When once the predetermined electrolytic solution is present in the cell compartment 43, during either the acid introducing or rinse stage, or at any other time, the valve M on the service line I5 will close, since the circuit to galvanometer 58 is unbalanced by the increased potential of the cell; causing a lateral shift in needle 96 and the completion of a circuit to elsetromagnet H which pulls rocker T2 to its downward position breaking the circuit to the solenoid in valve 9, and completing the circuit to the red signal bulb '52. As the rinse continues, excess acid and the sulphate will be eliminated from the softening tank 6 so that eventually the solution passing through the cell compartment 43 will be less than the undesired strength. This in turn will rebalance the circuit of galvanometer 58, causing it to approach the zero position through which it reverses the rockers H and I2 causing valve 49 to open by the energize.- tion of its solenoid and green signal bulb 53 to light.

It is clear then that if the rinse step is terminated by the return of lever IE to service position before an electrolyte of undesired strength is eliminated from the tank 8, the valve 49 will remain closed and prevent any such solution from going into the service lines. The operator will then be required to return the lever It to II to continue the rinsing until the strength of, the electrolyte corresponding to an excess regenerating solution is reduced, whereupon the valve I9 is caused to open.

I claim:

1. The combination 01' a zeolite water treatment apparatus for producing a service eilluent, conduits for raw water, service water, reagent and waste, a source of reagent, valve means for controlling the flow through said conduits to eifect the steps of regeneration of said appara-- tus including the flow through said service conduit, and a safety control including an electrical cell comprising a pair of electrodes of dissimilar metal disposed in the service efliuent from said apparatus ahead of said valve means, a motorized valve in said service conduit behind said valve means including a motor, means for supplying electrical energy to said motor for operating the same, and circuit means for controlling the supply of electrical energy to said motor in response to the change in electrical output of said cell with change in said eillucnt for closing and opening said motorized valve.

2. The combination or a zeolite water treatment apparatus for producing a service eilluent, a service line for conducting said eflluent to a' point of use, conduits for raw water, reagent and waste, a source or reagent, valve means for controlling the steps of regeneration of said apparatus including the flow throughsaid service line, an electrical cell comprising a pair of electrodes of dissimilar metal disposed in the eflluent from said apparatus ahead or said valve means, a motorized valve in the service line behind said valve means including a motor, means for supplying electrical energy to said motor .tor operating the same, and circuit means for controlling the supply oi. electrical energy to said motor in response to the output of said cell in the presence or absence of a predetermined electrolyte within the service line for closing and opening said motorized valve.

3.. In a water treatment device, a tank containing a base exchange material for producing a treated eihuent, conduits for raw Water, service water, reagent and waste, a source of reagent, a service valve for controlling the regeneration of said base exchange material, said conduits including a line between said tank and said service of excess regenerating solution to shut oil the service conduit in the presence oi! excess regenerating solution in said cell notwithstanding the position of said service valve.

' 4. The combnation in a water treatment device of a treatment tank for producing a treated eflluent, a service line, conduits for raw water, reagent and waste, a source of reagent, valve means for controlling the steps of regeneration including flow through said service line, an electrolytic cell immersed in said eflluent ahead of saidvalve means having an output responsive to the presence of regenerating material in said eflluent, a motorized valve in said service line including a motor, and means including a circuit and a chopper bar galvanometer electrically connected therein between said motor and said cell and responsive to the output of said cell for controlling the opening and closing of said valve in response to the condition 0! the effluent in said cell.

5. The combination in a water treatment device having a service line, conduits for raw water, reagent and waste, a source or reagent, and means for controlling the flow therethrough to regenerate the water treatment device, of a voltaic cell in said service line having the ellluent flowing from said water treating device as its electrolyte, an external circuit to said cell, circuit balancing means on said cell circuit consisting of a source of potential placed in opposition to the potential from said cell, a. relay, means responsive to a predetermined current in said external circuit upon unbalancing of said circuit by change in the output of said cell corresponding to change in the eiiluent to operate said relay, a valve located in the service line behind said cell through which the eflluent passes, electrical means for controlling said valve, and a circuit between said relay and said electrical means controlled by said relay for opening and closing said valve.

6. The combination in a flow control device for water treating apparatus for producing a desired eflluent of normal composition but capable of producing an undesirable eilluent of abnormal composition, of a voltaic cell having an eflluent flowternal circuit to the said cell, circuit balancing means for applying to said circuit a potential ing to effluent of abnormal composition in the external circuit to operate said relay, a valve located in the line through which the efiluent passesto a point of use, a motor for said valve, and a circuit between the said relay and motor controlled by said relay for closing said valve upon the appearance in said cell of eiiiuent of abnormal composition.

7. The combination in a liquid treatment apparatus for producing a desired effluent of normal composition but capable of producing an undesirable effluent of abnormal composition, of a voltaic cell having an effluent flowing from said apparatus as its electrolyte, a circuit external to said cell and including said cell, circuit balancing means'in said cell circuit for balancing the output of said cell in the presence'oi an efiiuent of normal composition, electrical signal means for indicating the condition of said apparatus, a relay for controlling said signal means, and means energized in reponse to unbalanced condition of said circuit and a predetermined current from said cell in said external circuit corresponding to the presenceof an effluent of abnormal compos'ition to operate said relay to indicate the presence in said cell of eiiiuent of normal and of abnormal composition.

8. The combination in a flow control device for liquid treatment apparatus of a voltaic cell having an eiliuent flowing from said apparatus as its electrolyte, a circuit external to said cell and including said cell, circuit balancing means in said cell circuit including a source of potential placed in opposition to the potential of said cell, the potential of said circuit balancing means being adapted to be overcome by the potential of said cell when efiluent of a predetermined composition is in said cell, a relay, a galvanometer, means electrically connecting said galvanometer to said relay and responsive to the presence of a current from said cell in said cell circuit to actuate said relay, a valve located in the line through which the effluent passes to a point of use, electrical means for operating said valve, and circuits disposed between said relay and said electrical means for actuating the same toclose the valve in response to the potential of said cell corresponding to the presence of said eliluent of predetermined composition in said cell and opening the same in response to the potential of said cell corresponding to the absence thereof.-

9. The combination in a water treatment apparatus of a tank, a zeolite bed contained therein, conduits for the introduction of raw water into the zeolite bed, a service line for the conveyance of treated water from the said tank, means for passing a regenerating solution through the zeolite bed, conduits for draining on the spent solution existing after the in oduction of the regenerating solution to the id zeolite bed, valve means controlling the steps of regeneration and return to service of the said apparatus, a cell having dissimilar electrodes, the said cell being so positioned with respect to the service line that liquid coming from the said tank to the service line will immerse the electrodes of the said cell, a valve located in the service line of the said softener between said valve means and a point of use, a motor for operating said valve, and election to the potential from said cell, said circuit trical means including circuits disposed between said cell and'said motor for closing said valve upon the presence of an electrolytic solution in said cell of greater than a predetermined concentration corresponding to the presence of an excess of regenerating solution and for opening said valve upon the presence of a solution in said cell of less than said concentration corresponding substantially to normal treated water.

10. The combination in a flow control device for liquid treatment apparatus of a voltaic cell having an effluent flowing from said apparatus as its electrolyte, an external circuit to said cell,

circuit balancing means on said cell circuit consisting of a source of potential placed in opposibalancing means being adapted to be overcome by the potential of said cell when eiiiuent of a predetermined composition is in said cell, a galvanometer responsive to the presence of a current from said cell in said cell circuit, electrical signal means for indicating the presence or absence of said predetermined solution in said cell, a relay for controlling said signal means, circuit means connecting said relay with said galvanometer to complete or break circuits to said relay, circuits between the relay and electrical signal means for controlling said signal means.

11. The combination ina flow control device for liquid treatment apparatus having a line for conducting eflluent flowing therefrom to a point of use, a'motorized valve in said line for controlling the flow therethrough including a motor, an energizing circuit therefor, a relay adapted in one position to energize said motor to close the valve and in another position to energize said motor to open the valve, a voltaic cell having said effluent as its electrolyte, a circuit external to said cell and including the same, circuit balancing means in said cell circuit including a source of potential in opposition to the potential from said cell, means for balancing said circuit to cause the potential of said cell to overbalance the potential of said balancing means when eiiluent of a predetermined composition is in said cell to cause a flow of current in said circuit, a chopper bar galvanometer having a conductive needle and motorized spaced switch means connected to said relay and positioned to be selectively closed at intervals dependent upon the position of said needle to energize said relay whereby to close said valve in response to the flow of current in said cell circuit and open said valve in response to substantial absence of current to prevent the flow of eiiluent to the point of use when said eiiiuent comprises said predeterminedcomposition.

12. The combination in a. water treatment apparatus of a tank containing a bed of zeolite, conduits for the introduction of raw water into the zeolite, a service line for the conveyance of treated water from said tank, means for passing Y a regenerating solution through said zeolite bed,

ation and return to service ofsaid apparatus, a.

valve located in the line through which the treated water of the tank passes, means for driving said valve between open and closed positions, an electrolytic cell having dissimilar electrodes, said cell being so positioned with respect to the service line that liquid coming from. said tank to the service line will immerse said electrodes, a circuit external to said cell and including said cell. a

relay for controlling said valve driving means, and means responsive to a predetermined current from said cell in said external circuit for operating said relay to move said valve to one of said positions and responsive to a different current in said circuit to move the valve to the other of said positions.

13. The combination in a water treatment apparatus of a tank containing a zeolite bed, conduits for the introduction of raw water into said tank, a service line for the conveyance of treated water from said tank, means for passing a regenerating solution through said bed, conduits for conducting the spent regenerating solution to drain, valve means controlling the steps of regeneration and return to service of said apparatus, a valve located in the line through which the treated water from the tank passes, means for driving said valve between open and closed positions, an electrolytic cell having dissimilar electrodes, said cell being 50 positioned with respect to the service line that liquid coming from said tank to the service line will immerse said electrodes, a circuit external to said cell and including the cell and circuit balancing means commieing a source of potential placed in opposition to the potential from said cell, a relay for controlling said valve driving means, and means responsive to an unbalanced condition of said external circuit resulting in a cell current in said external circuit corresponding to a changed output of said cell in the presence of an excess regenerating solution in said cell to energize said relay to move said valve to said closed position to prevent flow through said service line regardless of the position of said alve means.

14. The combination in a water treatment apparatus of a tank containing a zeolite bed, conduits for the introduction of raw water into said tank, a service line iorthe conveyance of. treated water from said tank, means for passing a regenerating solution through said bed, conduits for conducting the spent regenerating solution to drain, valve means controlling the steps of regeneration and return to service or said apparatus, a valve located in the line through which the treated water from the tank passes, means for driving said valve between open and closed posi-- tions, an electrolytic cell interposed in the liquid between said tank and said service line and responsive to the presence of regenerating material in said liquid, a circuit external to said cell and including, the cell and circuit balancing means comprising a source oi potential placed in opposition to the potential from said cell, a relay ior controlling said valve driving means, and means responsive to an unbalanced condition of said external circuit resulting in a cell current in said external circuit corresponding to a changed output of said cell. in the presence of an excess regenerating solution in said cell to energize said relay to move said valve to one of said positions and responsive to adiiferent current in said circuit to move the valve to the other of said positions whereby to prevent the flow of liquid through said service line in the presence of an excess regenerating solution at said electrodes regardless of the position of said valve means and to permit said flow in the presence of said treated water in said cell.

15. The combination recited in claim 14 wherein the last mentioned means comprises a chopper bar galvanometer having spaced contacts electrically connected to said relay for selectively actuating said relay to either of two positions corresponding to the open and closed positions of said valve, responsive to the cell current in said external circuit to thereby control the position of said valve. 

